Low-temperature hydrogen production from oxygenated hydrocarbons

ABSTRACT

Disclosed is a method of producing hydrogen from oxygenated hydrocarbon reactants, such as glycerol, glucose, or sorbitol. The method can take place in the vapor phase or in the condensed liquid phase. The method includes the steps of reacting water and a water-soluble oxygenated hydrocarbon having at least two carbon atoms, in the presence of a metal-containing catalyst. The catalyst contains a metal selected from the group consisting of Group VIII transitional metals, alloys thereof, and mixtures thereof. The disclosed method can be run at lower temperatures than those used in the conventional steam reforming of alkanes.

FEDERAL FUNDING STATEMENT

[0001] This invention was made with United States government supportawarded by NSF Grant No. 9802238 and DOE Grant No. DE-FG02-84ER13183.The United States has certain rights in this invention.

FIELD OF THE INVENTION

[0002] The invention is directed to a method of producing hydrogen (H₂)by vapor- and condensed liquid-phase reforming of oxygenatedhydrocarbons.

BACKGROUND OF THE INVENTION

[0003] Fuel cells have emerged as one of the most promising newtechnologies for meeting future global energy needs. In particular, fuelcells that consume hydrogen are proving to be environmentally clean,quiet, and highly efficient devices for power generation. However, whilehydrogen fuel cells have a low impact on the environment, the currentmethods for producing hydrogen require high-temperature steam reformingof non-renewable hydrocarbon fuels. Further still, thesehigh-temperature methods produce significant amounts of pollutingemissions and greenhouse gases such as carbon dioxide (CO₂).

[0004] A key challenge for promoting and sustaining the vitality andgrowth of the fuel cell industry (as well as the entire industrialsector of society) is to develop efficient and environmentally benigntechnologies for generating fuel, such as hydrogen, from renewableresources. Notably, if hydrogen fuel for consumption in fuel cells canbe generated efficiently from renewable sources, then non-renewableresources such as petroleum feedstocks can be used for other, morebeneficial, and less environmentally deleterious purposes. Moreover, thegeneration of energy from renewable resources such as biomass, reducesthe net rate of production of carbon dioxide, an important greenhousegas that contributes to global warming. This is because the biomassitself, i.e., plant material, consumes carbon dioxide during its lifecycle.

[0005] At present, the vast majority of hydrogen production isaccomplished via steam reforming of a hydrocarbon (usually methane) overa suitable catalyst. Conventional steam reforming takes place atconsiderably elevated temperatures, generally from about 400° C. to 700°C. or even higher (673 to 937 K and higher).

[0006] The net desired steam reformation reaction of a hydrocarbon isshown in reaction (1). The reaction requires a catalyst, conventionallya nickel-based catalyst on a modified alumina support.

C_(x)H_(2x+2) +xH₂O→xCO+(2x+1)H₂  (1)

[0007] The nickel catalyst is sensitive to sulfur poisoning, which canbe problematic. Hydrocarbon feedstocks produced from petroleum contain asignificant amount of sulfur. Therefore, the hydrocarbon reactants musthave the contaminating sulfur removed prior to undergoing steamreforming.

[0008] Conventional steam reforming is generally followed by one or morewater-gas shift (WGS) reactions (reaction (2)) that take place in asecond and perhaps a third reactor.

CO+H₂O→CO₂+H₂  (2)

[0009] The WGS reaction uses steam to convert the carbon monoxideproduced in reaction (1) to carbon dioxide and hydrogen. The WGSreaction is thus used to maximize the production of hydrogen from theinitial hydrocarbon reactants.

[0010] An entire, and typical, prior art process for the steamreformation of methane is illustrated schematically in FIG. 1. Thehydrocarbon feedstock is first desulfurized at 10. The desulfurizedfeedstock is then subjected to a first high-temperature, vapor-phasereforming reaction in a first high-temperature reaction chamber at 12.As noted earlier, this reaction generally uses a nickel-based catalyst.The products of the reaction at 12 are then swept into a second reactorfor a first WGS reaction 14. This first WGS reaction takes place atapproximately 300° C. to 350° C., using an iron catalyst. The productsof the reaction at 14 are swept into a third reactor for a second WGSreaction 16. This second WGS reaction takes place a reduced temperatureof from about 200° C. to 250° C. The products of the reaction at 16 arethen passed through a separator 18, where the products are separatedinto two streams: CO₂ and H₂O (the water which is pumped back into thereaction cycle at the beginning) and CO and H₂. The CO and H₂ streamfrom the separator 18 may also be subjected (at 20) to a finalmethanation reaction (to yield CH₄ and H₂) or an oxidation reaction toyield CO₂ and H₂.

[0011] It has been reported that it is possible to produce hydrogen viasteam reformation of methanol at temperatures near 277° C. (550 K). SeeB. Lindstrom & L. J. Pettersson, Int. J. Hydrogen Energy 26(9), 923(2001), and J. Rostrup-Nielsen, Phys. Chem. Chem. Phys. 3, 283 (2001).The approach described in these references uses a copper-based catalyst.These catalysts, however, are not effective to steam reform heavierhydrocarbons because the catalysts have very low activity for cleavageof C—C bonds. Thus, the C—C bonds of heavier hydrocarbons will not becleaved using these types of catalysts.

[0012] Wang et al., Applied Catalysis A: General 143, 245-270 (1996),report an investigation of the steam reformation of acetic acid andhydroxyacetaldehyde to form hydrogen. These investigators found thatwhen using a commercially available nickel catalyst (G-90C from UnitedCatalysts Inc, Louisville, Ky.), acetic acid and hydroxyacetaldehyde canbe reformed to yield hydrogen in high yield only at temperatures at orexceeding 350° C. Importantly, the nickel catalyst was observed todeactivate severely after a short period of time on stream.

[0013] A hydrogen-producing fuel processing system is described in U.S.Pat. No. 6,221,117 B1, issued Apr. 24, 2001. The system is a steamreformer reactor to produce hydrogen disposed in-line with a fuel cell.The reactor produces hydrogen from a feedstock consisting of water andan alcohol (preferably methanol). The hydrogen so produced is then fedas fuel to a proton-exchange membrane (PEM) fuel cell. Situated betweenthe reactor portion of the system and the fuel cell portion is ahydrogen-selective membrane that separates a portion of the hydrogenproduced and routes it to the fuel cell to thereby generate electricity.The by-products, as well as a portion of the hydrogen, produced in thereforming reaction are mixed with air, and passed over a combustioncatalyst and ignited to generate heat for running the steam reformer.

[0014] Conventional steam reforming has several notable disadvantages.First, the hydrocarbon starting materials contain sulfur which must beremoved prior to steam reformation. Second, conventional steam reformingmust be carried out in the vapor phase, and high temperatures (greaterthan 500° C.) to overcome equilibrium constraints. Because steamreformation uses a considerable amount of water which must also beheated to vaporization, the ultimate energy return is far less thanideal. Third, the hydrocarbon starting materials conventionally used insteam reforming are highly flammable. The combination of high heat, highpressure, and flammable reactants make conventional steam reforming areasonably risky endeavor.

[0015] Thus, there remains a long-felt and unmet need to develop amethod for producing hydrogen that utilizes low sulfur content,renewable, and perhaps non-flammable starting materials. Moreover, tomaximize energy output, there remains an acute need to develop a methodfor producing hydrogen that proceeds at a significantly lowertemperature than conventional steam reforming of hydrocarbons derivedfrom petroleum feedstocks. Lastly, there remains a long-felt and unmetneed to simplify the reforming process by developing a method forproducing hydrogen that can be performed in a single reactor.

SUMMARY OF THE INVENTION

[0016] The invention is directed to a method of producing hydrogen viathe reforming of an oxygenated hydrocarbon feedstock. The methodcomprises reacting water and a water-soluble oxygenated hydrocarbonhaving at least two carbon atoms, in the presence of a metal-containingcatalyst. The catalyst comprises a metal selected from the groupconsisting of Group VIII transitional metals, alloys thereof, andmixtures thereof.

[0017] In a first embodiment of the invention, the water and theoxygenated hydrocarbon are reacted at a temperature of from about 100°C. to about 450° C. More preferably, the reaction takes place at atemperature of from about 100° C. to about 300° C. In either instance,the reaction is run at a pressure where the water and the oxygenatedhydrocarbon are gaseous.

[0018] In a second embodiment of the invention, the water and theoxygenated hydrocarbon are reacted at a temperature not greater thanabout 400° C. and at a pressure where the water and the oxygenatedhydrocarbon remain condensed liquids.

[0019] In the second embodiment, it is preferred that the water and theoxygenated hydrocarbon are reacted at a pH of from about 4.0 to about10.0.

[0020] In both the first and second embodiments, it is preferred thatthe catalyst comprise a metal selected from the group consisting ofnickel, palladium, platinum, ruthenium, rhodium, iridium, alloysthereof, and mixtures thereof Optionally, the catalyst may also befurther alloyed or mixed with a metal selected from the group consistingof Group IB metals, Group IIB metals, and Group VIIb metals, and fromamong these, preferably copper, zinc, and/or rhenium. It is also muchpreferred that the catalyst be adhered to a support, such as silica,alumina, zirconia, titania, ceria, carbon, silica-alumina, silicanitride, and boron nitride. Furthermore, the active metals may beadhered to a nanoporous support, such as zeolites, nanoporous carbon,nanotubes, and fullerenes.

[0021] The support itself may be surface-modified to remove, cap, orotherwise modify surface moieties, especially surface hydrogen andhydroxyl moieties that may cause localized pH fluctuations. The supportcan be surface-modified by treating it with silanes, alkali compounds,alkali earth compounds, and the like. A preferred modified support issilica that has been treated with trimethylethoxysilane.

[0022] In the second embodiment of the invention, where the water andthe oxygenated hydrocarbon remain condensed liquids, the method can alsofurther comprise reacting the water and the water-soluble oxygenatedhydrocarbon in the presence of a water-soluble salt of an alkali oralkali earth metal. The addition of these salts tends to increase theoverall production of hydrogen realized in the method. It is preferredthat the water-soluble salt is an alkali or an alkali earth metalhydroxide, carbonate, nitrate, or chloride salt. Potassium hydroxide(KOH) is preferred.

[0023] In both the first and second embodiments, it is much preferredthat the water-soluble oxygenated hydrocarbon has a carbon-to-oxygenratio of 1:1. Particularly preferred oxygenated hydrocarbons includeethanediol, ethanedione, glycerol, glyceraldehyde, aldotetroses,aldopentoses, aldohexoses, ketotetroses, ketopentoses, ketohexoses, andalditols. From among the oxygenated hydrocarbons having six carbonatoms, glucose and sorbitol are preferred. Ethanediol, glycerol, andglyceraldehyde are the preferred oxygenated hydrocarbons from amongthose having less than six carbon atoms.

[0024] The invention will also function with mixed feedstocks ofoxygenated hydrocarbons, that is, feedstocks containing mixtures of twoor more oxygenated hydrocarbons.

[0025] The present invention thus provides methods for producinghydrogen via a low-temperature, catalytic reforming of oxygenatedhydrocarbon compounds such as ethanediol, glycerol, sorbitol, glucose,and other water-soluble carbohydrates. For the purpose of the presentinvention, “reforming” or “steam reforming” is defined as the reactionof an oxygenated hydrocarbon feedstock to yield hydrogen and carbondioxide.

[0026] A principal advantage of the subject invention is that theoxygenated hydrocarbon reactants can be produced from renewableresources, such as biomass. Thus, the present method can be used togenerate a fuel source, namely hydrogen, from an abundant and fullyrenewable source. Also, because living plant matter consumes carbondioxide, the use of these feedstocks in power generation applicationsdoes not result in a net increase of carbon dioxide vented to theatmosphere.

[0027] Another equally important advantage of the present method is thatit functions at a much lower temperature than conventional steamreforming of hydrocarbons. Conventional steam reforming of hydrocarbonsrequires operating temperatures greater than about 500° C. (773 K). Thesubject method, however, is able reform aqueous solutions or gaseousmixtures of oxygenated hydrocarbons to yield hydrogen, at temperaturesof from about 100° C. to about 450° C. in the vapor phase. Morepreferably still, the vapor phase reaction is run at a temperature offrom about 100° C. to about 300° C. In the condensed liquid phase, thereaction is run at temperatures not greater than about 400° C.

[0028] Another beneficial aspect of the present invention is that itallows for the reforming of the oxygenated hydrocarbon and asimultaneous WGS reaction to take place in a single reactor.

[0029] Another distinct advantage of the present invention is thatoxygenated hydrocarbons are far less dangerous than are the conventionalhydrocarbons normally used in steam reformation. Thus, the presentinvention yields hydrogen from such relatively innocuous substances asethanediol, glycerol, glucose, and sorbitol (as compared to the highlyflammable methane or propane that are used in conventional reformingmethods).

[0030] Still another advantage of the present invention is that when themethod is carried out in the condensed liquid phase, it eliminates theneed to vaporize water to steam. This is a critical concern inlarge-scale operations due to the high energy costs required to vaporizelarge amounts of water. The heat of vaporization of water is more than2000 kJ per mole. By eliminating the need to vaporize the water, theamount of energy that must be input into the claimed method to yieldhydrogen is greatly reduced. The overall energy yield, therefore, isconcomitantly increased.

[0031] Thus, the subject method provides a means to convert oxygenatedhydrocarbons to yield hydrogen, using a single reactor bed and reactorchamber, and at low temperatures. Such a reactor system can befabricated at a reduced volume and can be used to produce hydrogen thatis substantially free of contaminates for use in portable fuel cells orfor use in applications in remote locations.

[0032] The hydrogen produced using the present invention can be utilizedin any process where hydrogen is required. Thus, the hydrogen can beused, for example, as a fuel for fuel cells. The hydrogen can be usedfor producing ammonia, or it could be used in the refining of crude oil.The method yields a hydrogen stream that has a very low sulfur content.When low sulfur content reactants are utilized, the method yields ahydrogen stream that is substantially free of both sulfur and carbonmonoxide. This type of hydrogen stream is highly suitable for use infuel cells, where sulfur and/or carbon monoxide can poison the catalystslocated at the electrodes of each fuel cell.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a schematic diagram of a PRIOR ART method of steamreforming a hydrocarbon feedstock to yield hydrogen.

[0034]FIG. 2 is a graph depicting the thermodynamics for the conversionof hydrocarbons and oxygenated hydrocarbons to carbon monoxide andhydrogen (H₂).

[0035]FIG. 3 is a graph depicting, on the same temperature scale, thethermodynamics for the conversion of oxygenated hydrocarbons to carbonmonoxide and H₂, and the vapor pressures of the oxygenated hydrocarbonreactants as a function of temperature.

[0036]FIG. 4 is a graph depicting the temperature at which ΔG°/RT isequal to zero versus the number of carbons in the reactants for thesteam reforming alkanes (trace 10) and oxygenated hydrocarbons (trace12) having a carbon-to-oxygen ratio of 1:1. This figure also includes aplot (trace 14) of the temperature at which the vapor pressure of theoxygenated hydrocarbons is equal to 0.1 atm.

[0037]FIG. 5 is a schematic diagram of a reactor system that can be usedto carry out the condensed liquid phase reforming of oxygenatedhydrocarbons.

[0038]FIG. 6 is a schematic diagram of a one-reactor approach forreforming oxygenated hydrocarbons into CO and H₂, followed by a WGSreaction to maximize the production of H₂.

[0039]FIG. 7 shows the vapor-phase reforming of ethanediol over a 4 wt %Ru/SiO₂ catalyst system at 300° C. and 1 atm as detailed in Example 7.

[0040]FIG. 8 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, and a molar water-to-carbon ratio of 15 over mono-metalliccatalyst systems containing Rh, Ni, Ru, Ir, Co, or Fe, as detailed inExample 9.

[0041]FIG. 9 shows vapor-phase reforming of ethanediol at 250° C. and 1atm, and a water-to-carbon molar ratio of 15 over two different nickelcatalyst systems (1 wt % Ni/SiO₂ and 15 wt % Ni/MgO—Al₂O₃), as detailedin Example 9.

[0042]FIG. 10 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, and a water-to-carbon ratio of 15 over a bimetallic catalystsystem (Ni—Pd) as compared to monometallic Rh/SiO₂, Pd, and Ni catalystsystems, as detailed in Example 9.

[0043]FIG. 11 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, and a water-to-carbon ratio of 15 over various catalystsystems (Rh, Ni—Pt, Pt, and Ni), as detailed in Example 9.

[0044]FIG. 12 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, and a water-to-carbon ratio of 15 over various catalystsystems (Rh, Ru—Pd, Pd, and Ru), as detailed in Example 9.

[0045]FIG. 13 shows the vapor-phase reforming of sorbitol at 425° C. and1 atm, at a water-to-carbon ratio of 32 over silica-supported rhodiumcatalyst systems as detailed in Example 10.

[0046]FIG. 14 shows the vapor-phase reforming of sorbitol at 425° C. and1 atm, at a water-to-carbon ratio of 32 over silica-supported rhodiumcatalyst systems as detailed in Example 10, in the presence and absenceof added helium.

[0047]FIG. 15 shows the results for the condensed liquid phase reformingof a 10 wt % sorbitol solution over a 5 wt % Pt/SiO₂ catalyst system at225° C., followed by liquid phase reforming of a 10 wt % glucosesolution. See Example 12.

[0048]FIG. 16 shows the condensed liquid phase reforming of a 10 wt %sorbitol solution over a modified 5 wt % Pt/SiO₂ catalyst system. SeeExamples 11 and 12.

DETAILED DESCRIPTION OF THE INVENTION

[0049] The present invention is an energy efficient method for steamreforming oxygenated hydrocarbons at considerably lower temperaturesthan previously possible. The reaction can take place in the vaporphase, in the same fashion as conventional steam reforming reactions(although at a much lower temperature). The reaction can also take placein the condensed liquid phase, in which case the reactants (water and anoxygenated hydrocarbon) remain condensed liquids, as opposed to beingvaporized prior to reaction.

[0050] As used herein to describe the present invention, the terms“reforming,” “steam reforming,” and “steam reformation” are synonymous.These terms shall generically denote the overall reaction of anoxygenated hydrocarbon and water to yield a hydrogen stream, regardlessof whether the reaction takes place in the gaseous phase or in thecondensed liquid phase. Where the distinction is important, it shall beso noted.

[0051] When the steam reforming of oxygenated hydrocarbons is carriedout in the liquid phase, the present invention makes it possible toproduce hydrogen from aqueous solutions of oxygenated hydrocarbonshaving limited volatility, such as glucose and sorbitol.

[0052] Abbreviations and Definitions:

[0053] “GC”=gas chromatograph or gas chromatography.

[0054] “GHSV”=gas hourly space velocity.

[0055] “psig”=pounds per square inch relative to atmospheric pressure(i.e., gauge pressure).

[0056] “Space Velocity”=the mass/volume of reactant per unit of catalystper unit of time.

[0057] “TOF”=turnover frequency.

[0058] “WHSV”=weight hourly space velocity=mass of oxygenated compoundper mass of catalyst per h.

[0059] “WGS”=water-gas shift.

[0060] Thermodynamic Considerations:

[0061] As noted above, the stoichiometric reaction for steam reformingof alkanes to yield hydrogen and carbon monoxide is given by reaction(1):

C_(x)H_(2x+2) +xH₂O→xCO+(2x+1)H₂  (1)

[0062] The stoichiometric reaction for steam reforming of carbonmonoxide to yield hydrogen and carbon dioxide is given by the water-gasshift (WGS) reaction, reaction (2):

CO+H₂O→CO₂+H₂  (2)

[0063] The stoichiometric reaction for steam reforming of an oxygenatedhydrocarbon having a carbon-to-oxygen ration of 1:1 is given by reaction(3):

C_(x)H_(2y)O_(x) →nCO+yH₂  (3)

[0064]FIG. 2 is a graph depicting the changes in the standard Gibbs freeenergy (ΔG°) associated with reaction (1) and (3) for a series ofalkanes (CH₄, C₂H₆, C₃H₈, C₄H₁₀, C₅H₁₂, and C₆H₁₄) and oxygenatedhydrocarbons having a carbon-to-oxygen ratio of 1:1 (CH₃OH, C₂H₄(OH)₂,C₃H₅(OH)₃, and C₆H₈(OH)₆). The values plotted in FIG. 2 have beennormalized per mole of CO. The ΔG° data points shown in FIG. 2 have beendivided by RT. Thus, FIG. 2 is a plot having ΔG°/RT on the Y-axis andtemperature (in Kelvins) on the X-axis. It can be seen from FIG. 2 thatthe steam reforming of C₁ to C₆ alkanes to produce CO and H₂ isthermodynamically favorable (i.e., ΔG° is negative) at significantlyhigher temperatures than those required for the steam reforming of theoxygenated hydrocarbons having the same number of carbon atoms.

[0065] For example, the steam reforming of methane, trace 10 in FIG. 2,becomes thermodynamically favorable only at temperatures above about 900K. In contrast, the steam reforming of the oxygenated hydrocarbons(traces 14, 16, 18, 20, and 22) is favorable at temperatures above about400 K.

[0066] Reactions (4) and (5) represent the reforming of CH₂ groups inalkanes as compared to CH(OH) groups in oxygenated hydrocarbons:

C₃H₈+H₂O→C₂H₆+CO+2H₂  (4)

C₃H₈O₃→C₂H₆O₂+CO+H₂  (5)

[0067] The value of ΔG°/RT for reaction (4), involving CH₂ groups, isequal to zero at a temperature of about 635 K. In contrast, ΔG°/RT forreaction (5), involving CH(OH) groups, is equal to zero at a temperatureof about 320 K. Thus, according to the present invention, the steamreforming of oxygenated hydrocarbons, especially hydrocarbons having acarbon-to-oxygen ratio of 1:1 (the preferred ratio) is thermodynamicallyfavorable at temperatures far lower than the analogous steam reformingreaction of alkanes.

[0068]FIG. 2 also shows that the value of ΔG° for the WGS reaction(reaction (3), trace 12 of FIG. 2) is more favorable at lowertemperatures. This reveals that the conversion of CO (produced inreactions (1) and (2)) to CO₂ and H₂ is more favorable at the lowertemperatures associated with the reforming of oxygenated hydrocarbons.Therefore, the steam reforming of oxygenated hydrocarbons provides alow-temperature route to the formation of CO₂ and H₂, provided thatappropriate catalysts are developed for operation at these lowtemperature reaction conditions.

[0069] As a general proposition (albeit with several exceptions), therate of cleavage of C—H bonds on metal surfaces is faster than thecleavage of C—C bonds on metal surfaces. Accordingly, the steamreforming of, for example, methanol to produce CO and H₂, would beexpected to be relatively facile compared to the reforming of ethanediol(i.e., ethylene glycol) to yield the same product mix. In the case ofmethanol, the general proposition holds true: The steam reforming ofmethanol can be achieved at low temperatures over catalysts (such ascopper) that do not readily cleave C—C bonds. In contrast, the steamreforming of ethanediol will not readily take place under theseconditions using the same copper catalysts because the catalyst does noteffectively catalyze the cleavage of C—C bonds.

[0070] Also, because methanol itself is typically produced from a CO andH₂ stream that is derived from petroleum processing, the steam reformingof methanol does not represent the production of energy from a renewableresource. For this reason, appropriate catalysts for use in the presentinvention must show good activity for the cleavage of C—C bonds.

[0071] The thermodynamic trends shown in FIG. 2 also indicate thatappropriate catalysts for use in the present invention must not showhigh activity for the cleavage of C—O bonds. Consider, for example, thesteam reforming of ethanediol, reaction (6), followed by cleavage of theC—O bond in carbon monoxide to form methane and water, reaction (7),leading to the overall process given by reaction (8):

C₂H₄(OH)₂→2CO+3H₂ ΔG°/RT=−14 (at 470 K)  (6)

CO+3H₂→CH₄+H₂O ΔG°/RT=−26 (at 470 K)  (7)

C₂H₄(OH)₂→CO+CH₄+H₂O ΔG°/RT=−40 (at 470 K)  (8)

[0072] Because reaction (7) is the reverse of the steam reforming ofmethane, it is apparent from FIG. 2 that reaction (7) becomes veryfavorable at low temperatures. Thus, for example, at a temperature of470 K, the values of ΔG°/RT for reactions (6) and (7) are equal to −14and −26, respectively. This leads to a very favorable ΔG°/RT value of−40 for the overall reaction (8). Therefore, a reforming catalyst thatis readily able to cleave C—C and C—O bonds would convert ethanediol atlow temperatures to a mixture of CO and CH₄, instead of the desiredproduct mixture of CO and H₂. The CO and H₂ product mixture is preferredbecause it is followed by the production of CO₂ and H₂ by the WGSreaction. Clearly then, the production of CH₄ is undesirable for a fuelcell application because the production of CH₄ creates a significantloss of H₂ from the system.

[0073] The above behavior for steam reforming of oxygenated hydrocarbonshaving a carbon-to-oxygen ratio of 1:1 can be extended to the reformingat low temperatures of oxygenated hydrocarbons having a carbon-to-oxygenratio higher than 1:1. In particular, upon reforming, these oxygenatedhydrocarbons having higher carbon-to-oxygen ratios yield CO and H₂, plusthe formation of the appropriate alkane. For example, consider theconversion of ethanol according to the following reaction:

C₂H₅OH→CO+H₂+CH₄ ΔG°/RT=−16 (at 470 K)  (9)

[0074] It can be seen from in FIG. 2, trace 22, that reaction (9) isvery favorable at low temperatures. At 470 K, the value of ΔG°/RT forreaction (9) is equal to −16. Thus, according to the present invention,a catalyst is used to convert ethanol at low temperatures to produce H₂(which can be used for any purpose, such as to power a fuel cell) and toco-generate methane for some other application (such as a combustionprocess to produce heat). To achieve this co-generation operation,however, it is necessary that the catalyst does not facilitate thereaction of ethanol with H₂ to produce ethane:

C₂H₅OH+H₂→C₂H₆+H₂O ΔG°/RT=−16 (at 470 K)  (10)

[0075] As noted, at 470 K, the value of ΔG°/RT for reaction (10) is −24,a value more negative than that for reaction 9. This again demonstratesthe importance that the catalyst to be used in the present inventionshould not show high activity for the cleavage of C—O bonds.

[0076] Vapor-Phase Reforming vs. Condensed Liquid-Phase Reforming:

[0077] The steam reforming of hydrocarbons typically takes place in thevapor phase. Therefore, the vapor-phase steam reforming at lowtemperatures of oxygenated hydrocarbons may (under certaincircumstances) be limited by the vapor pressure of the reactants. FIG. 3is a graph that depicts, on the same temperature scale, the vaporpressure of various oxygenated hydrocarbons as a function of temperatureand the thermodynamics of these same oxygenated hydrocarbons in thereforming reaction yielding CO and H₂. The upper portion of FIG. 3 showsplots of the vapor pressure (atm) versus temperature (K) for oxygenatedhydrocarbons having a carbon-to-oxygen ratio of 1:1 (CH₃OH, C₂H₄(OH)₂,C₃H₅(OH)₃, and C₆H₈(OH)6). The lower portion of FIG. 3 shows plots ofΔG°/RT versus temperature for these same reactants.

[0078] In evaluating FIG. 3, assume (for sake of simplicity) that thevapor pressure of the hydrocarbon reactant should be higher than about0.1 atm for economically-feasible vapor-phase steam reforming. Thus, asit can be seen in FIG. 3, low-temperature steam reforming of methanol(vapor pressure=trace 10, ΔG°/RT=trace 12) is not fundamentally limitedby the vapor pressure of the methanol reactant, but is fundamentallylimited by the value of ΔG°/RT for the corresponding stoichiometricreaction. This is because a vapor pressure of 0.1 atm of methanol isachieved at a lower temperature (290 K) than the temperature at whichΔG°/RT becomes equal to zero (410 K). Thus, at the temperature whereΔG°/RT becomes favorable for the steam reforming of methanol (410 K),the methanol is already entirely vaporized.

[0079] In contrast, the vapor-phase steam reforming of heavieroxygenated hydrocarbons may be limited by the vapor pressure of thesereactants. For example, it can be seen in FIG. 3 that the vapor-phasesteam reforming of ethanediol (traces 14 and 16) and glycerol (traces 18and 20) should be carried out at temperatures higher than about 400 Kand 500 K, respectively. In contrast to these moderate temperatures, thevapor-phase steam reforming of sorbitol must be carried out attemperatures higher than about 700 K, a temperature at which the vaporpressure of sorbitol is roughly 0.1 atm.

[0080]FIG. 4 is a graph depicting the temperature (K, on the Y-axis) atwhich ΔG°/RT is equal to zero versus the number of carbons in thereactants for the steam reforming alkanes (trace 10) and oxygenatedhydrocarbons (trace 12) having a carbon-to-oxygen ratio of 1:1. Thisfigure also includes a plot (trace 14) of the temperature at which thevapor pressure of the oxygenated hydrocarbons is equal to 0.1 atm. Asshown in FIG. 3, the plots superimposing ΔG°/RT and vapor pressureintersect at carbon numbers between 1 and 2 for these oxygenatedhydrocarbons (that is, between methanol and ethanediol). A closeanalysis of FIG. 4 indicates the following points: (1) the vapor-phasereforming of methanol (1 carbon atom) can be carried out at temperaturesthat are lower by about 500 K as compared to methane; (2) thevapor-phase reforming of ethanediol (2 carbon atoms) can be carried outat temperatures that are lower by about 340 K as compared to ethane;and, (3) the vapor-phase reforming of glycerol (i.e., propanetriol, 3carbon atoms) can be carried out at temperatures that are lower by about230 K as compared to propane.

[0081] In contrast to these lighter oxygenated hydrocarbons, thevapor-phase reforming of sorbitol (6 carbon atoms) must be carried outat temperatures that are similar to those for hexane, roughly 680 to 700K. Thus, there is a tremendous energy advantage in vapor-phase reformingof short-chain oxygenated hydrocarbons as compared to the correspondingalkanes. The advantage in operating at lower temperatures forvapor-phase reforming of lighter oxygenated hydrocarbons compared toreforming of alkanes having the same carbon number is actually even moresignificant than as presented in FIG. 4. In particular, the values ofΔG°/RT used to construct plots 10 and 12 of FIG. 4 do not take intoaccount the WGS reaction. That is, the ΔG°/RT values plotted in FIG. 4assume that the product mixture is H₂ and CO, rather than CO₂. In otherwords, the ΔG°/RT values shown in FIG. 4 do not account for a subsequentWGS reaction, which will result in the production of still morehydrogen. As discussed above, the WGS reaction is more favorable at thelower temperatures appropriate for the steam reforming of oxygenatedhydrocarbons. Thus, steam reforming of oxygenated hydrocarbons is a farmore efficient reaction than the steam reforming reaction using thecorresponding alkane.

[0082] The thermodynamic considerations summarized in FIG. 4 show thatit is possible to conduct the vapor-phase steam reforming of methanol,ethanediol and glycerol at significantly lower temperatures as comparedto the corresponding alkanes having the same number of carbon atoms.

[0083] While this low-temperature advantage does not exist for thevapor-phase steam reforming of sorbitol, unlike hexane, sorbitol isreadily obtained from a renewable resource (i.e., glucose). In contrast,hexane is derived from non-renewable petroleum. Therefore, thevapor-phase steam reforming of sorbitol has very important environmentaland long-term use advantages as compared to using hexane.

[0084] Another aspect of the invention also is revealed by a closeinspection of FIG. 4 and that is that the advantages of producing H₂from steam reforming of sorbitol can be achieved more fully byconducting the reaction in the condensed liquid phase. By conducting thereforming reaction in the condensed liquid phase, rather than the gasphase, the need to vaporize the reactant is eliminated. (Thus, theenergy required to surmount the heat of vaporization of the reactants islikewise eliminated.) In the case of sorbitol in particular,liquid-phase reforming of sorbitol can be carried out at a temperaturethat is roughly 360 K lower than the temperature required to reformhexane in the condensed liquid phase.

[0085] Using reforming of oxygenated hydrocarbons (either in the vaporphase or the condensed liquid phase), it becomes possible to produce H₂from carbohydrate feedstocks, such as glucose and corn starch, that havelimited volatility. For example, the reforming of glucose would proceedaccording to reaction (11):

⅙C₆H₁₂O₆ (solid)→CO (gas)+H₂ (gas)  (11)

[0086] The thermodynamic behavior for the reforming of glucose thus issimilar to (even perhaps identical to) that for the reforming of otheroxygenated hydrocarbons having a carbon-to-oxygen ratio of 1:1.

[0087] The liquid phase reforming of starch to produce H₂ would firstinvolve the hydrolysis of starch to form glucose, followed by thereforming of glucose according to reaction (11). The thermodynamicproperties for the hydrolysis reaction can be estimated from theconversion of diethyl-ether with water to form ethanol:

C₂H₅OC₂H₅+H₂O→2C₂H₅OH  (12)

[0088] The value of ΔG°/RT per mole of ethanol formed in reaction (12)is slightly positive. This slightly unfavorable value, however, is morethan compensated for by the more negative value of ΔG°/RT for reaction(11). Thus, at temperatures above 400 K, the thermodynamic behavior forthe reforming of starch to form H₂ is very favorable. Further still,note that reaction (11) is based on the formation of 1 mole of CO, whilereaction (12) represents the formation of 1 mole of glucose. Therefore,the value of ΔG°/RT for reaction (12) should be divided by 6 forcomparison with the value of ΔG°/RT for reaction (11). This adjustmentmakes the thermodynamic properties for the reforming of starch to formH₂ even more favorable.

[0089] Taken in conjunction, the thermodynamic properties presented inFIGS. 2, 3, and 4, show that it is possible to conduct the reforming ofglucose and starch at moderate temperatures (e.g., above about 400 K).Thus, steam reforming of carbohydrates in the condensed liquid phaseprovides a low-temperature alternative to the production of H₂ frompetroleum. Furthermore, this low-temperature route for the production ofH₂ from carbohydrates utilizes a renewable feedstock. This combinationof low-temperature processing and utilization of renewable resourcesoffers a unique opportunity for efficient and environmentally-benignenergy generation.

[0090] Reactor System:

[0091] An illustrative reactor system for carrying out the presentlyclaimed method is depicted schematically in FIG. 5. Note that FIG. 5illustrates an exemplary system. Many other reactor configurations couldbe utilized with equal success.

[0092] As shown in FIG. 5, a reactor 18 is disposed within a furnace 20.Liquid reactants are introduced into the reactor 18 via pump 16. Asshown in the figure, the pump 16 is a small-scale, HPLC pump. (FIG. 5depicts the prototype reactor that was used to conduct the experimentsdescribed in Examples 11 and 12.) Obviously, for full-scale hydrogenproduction, a much larger pump would be utilized.

[0093] Nitrogen supply 10 and hydrogen supply 12 are provided tomaintain the overall pressure of the system and the partial pressure ofhydrogen within the system chambers in and downstream of the reactor 18.Mass flow controllers 14 are provided to regulate the introduction ofnitrogen and hydrogen into the system.

[0094] A heat exchanger 22 is provided to reduce the temperature of theproducts exiting the reactor 18. As shown in FIG. 5, the heat exchangeris a water cooler, but any type of heat exchanger will suffice. Theproducts are then swept into separator 24. The design of the separatoris not critical to the function of the invention, so long as itfunctions to separate gaseous products from liquid products. Manysuitable separators to accomplish this function are known in the art,including distillation columns, packed columns, selectively-permeablemembranes, and the like. Pressure regulator 28 and back-pressureregulator 26 serve to monitor and maintain the pressure of the systemwithin the set value or range.

[0095] In a typical condensed liquid phase reforming reaction accordingto the present invention, a suitable metal-containing catalyst,preferably a metal catalyst impregnated on a support such as silica, isplaced into the reactor 18. The metal catalyst is then reduced byflowing hydrogen from 12 into the reactor at a temperature of roughly498 K. The pressure of the system is then increased to 300 psig usingnitrogen from 10. The pump 16 is then used to fill the reactor 18 withan aqueous solution of reactant oxygenated hydrocarbon (for example,sorbitol).

[0096] The liquid effluent from the reactor is then cooled in the heatexchanger 22 and combined with nitrogen flowing at the top of theseparator. The gas/liquid effluent is then separated at 24. The productgas stream can then be analyzed by any number of means, with gaschromatography being perhaps the most easily implemented, in-lineanalysis. Likewise, the effluent liquid may also be drained andanalyzed.

[0097] One of the primary advantages of the present invention is that ittakes place at greatly reduced temperatures as compared to conventionalsteam reforming of hydrocarbons. Thus, the inventive method can beoptimized to perform a steam reforming reaction and a WGS reactionsimultaneously, in the same reactor, to yield a product comprised almostentirely of H₂, CO₂, and H₂O. This is shown schematically in FIG. 6.Here, a single-stage reactor 18 is shown, in which the reformingreaction and the WGS reaction take place simultaneously. The productsare then swept into a separator 24 (shown in FIG. 6 as a membraneseparator) where the hydrogen is separated from the CO₂ and the water.The hydrogen so produced can be used for any purpose where hydrogen isneeded.

[0098] Thus, the liquid-phase reforming method of the present inventiongenerally comprises loading a metallic catalyst into a reactor andreducing the metal (if necessary). An aqueous solution of the oxygenatedhydrocarbon is then introduced into the reactor and the solution isreformed in the presence of the catalyst. The pressure within thereactor is kept sufficiently high to maintain the water and oxygenatedhydrocarbon in the condensed liquid phase at the selected temperature.The resulting CO is then converted to additional hydrogen and carbondioxide via a WGS reaction, a reaction that can occur within the samereactor. It is also possible that the catalyst may convert the reactantto CO₂ and H₂ without passing through a CO intermediate. The vapor-phasereforming method of the invention proceeds in essentially the samefashion, with the exception that the reactants are allowed to vaporizeand the reaction takes place in the gas phase, rather than in thecondensed liquid phase.

[0099] Oxygenated Hydrocarbons:

[0100] Oxygenated hydrocarbons that can be used in the present inventionare those that are water-soluble and have at least two carbons.Preferably, the oxygenated hydrocarbon has from 2 to 12 carbon atoms,and more preferably still from 2 to 6 carbon atoms. Regardless of thenumber of carbon atoms in the oxygenated hydrocarbon, it is muchpreferred that the hydrocarbon has a carbon-to-oxygen ratio of 1:1.

[0101] Preferably, the oxygenated hydrocarbon is a water-solubleoxygenated hydrocarbon selected from the group consisting of ethanediol,ethanedione, glycerol, glyceraldehyde, aldotetroses, aldopentoses,aldohexoses, ketotetroses, ketopentoses, ketohexoses, and alditols. Fromamong the 6-carbon oxygenated hydrocarbons, aldohexoses andcorresponding alditols are preferred, glucose and sorbitol being themost preferred. From among the smaller compounds, ethanediol, glyceroland glyceraldehyde are preferred. Sucrose is the preferred oxygenatedhydrocarbon having more than 6 carbon atoms.

[0102] Vapor phase reforming requires that the oxygenated hydrocarbonreactants have a sufficiently high vapor pressure at the reactiontemperature so that the reactants are in the vapor phase. In particular,the oxygenated hydrocarbon compounds preferred for use in the vaporphase method of the present invention include, but are not limited to,ethanediol, glycerol, and glyceraldehyde. Where the reaction is to takeplace in the liquid phase, glucose and sorbitol are the most preferredoxygenated hydrocarbons. Sucrose is also a preferred feedstock for usein the liquid phase.

[0103] In the methods of the present invention the oxygenatedhydrocarbon compound is combined with water to create an aqueoussolution. The water-to-carbon ratio in the solution is preferably fromabout 2:1 to about 20:1. This range is only the preferred range.Water-to-carbon ratios outside this range are included within the scopeof this invention.

[0104] It is much preferred that the water and the oxygenatedhydrocarbon are reacted at a pH of from about 4.0 to about 10.0.

[0105] Catalysts:

[0106] As discussed above, the metallic catalyst to be used in thepresent method may be any system that is capable of cleaving the C—Cbonds of a given oxygenated hydrocarbon compound faster than the C—Obonds of that compound under the chosen reaction conditions. Preferably,the metallic catalyst should have minimal activity toward the cleavageof C—O bonds. Use of a catalyst system having high activity for C—O bondcleavage can result in the formation of undesired by-products, such asalkanes.

[0107] The metallic catalyst systems preferred for use in the presentinvention comprise one or more Group VIII transitional metals, alloysthereof, and mixtures thereof, preferably (although not necessarily)adhered to a support. From among these metals, the most preferred arenickel, palladium, platinum, ruthenium, rhodium, and iridium, alloysthereof, and mixtures thereof Platinum, ruthenium, and rhodium are themost preferred.

[0108] The Group VIII transition metal catalyst may optionally bealloyed or admixed with a metal selected from the group consisting ofGroup IB metals, Group IIB metals, and Group VIIb metals. The amount ofthese added metals should not exceed about 30% of the weight of theGroup VIII transition metal catalyst present. The preferred optionalmetals for inclusion in the catalyst are copper, zinc, and rhenium,alloys thereof, and mixtures thereof.

[0109] If loaded onto a support, the metallic catalyst should be presentin an amount of from about 0.25% to about 50% by total weight of thecatalyst system (the weight of the support being included), with anamount of from about 1% to 30% by total weight being preferred.

[0110] If a support is omitted, the metallic catalyst should be in avery finely powdered state, sintered, or in the form of a metallic foam.Where a support is omitted, metal foams are preferred. Metal foams areextremely porous, metallic structures that are reasonably stiff (theyare sold in sheets or blocks). They are very much akin in structure toopen-cell foamed polyurethane. Gas passing through a metal foam isforced through an extremely tortuous path, thus ensuring maximum contactof the reactants with the metal catalyst. Metal foams can be purchasedcommercially from a number of national and international suppliers,including Recemat International B.V. (Krimpen aan den Ijssel, theNetherlands), a company that markets “RECEMAT”-brand metal foam. In theUnited States, a very wide variety of metal foams can be obtained fromReade Advanced Materials (Providence, R.I. and Reno, Nev.).

[0111] It is preferred, however, that a support be used. The supportshould be one that provides a stable platform for the chosen catalystand the reaction conditions. The supports include, but are not limitedto, silica, alumina, zirconia, titania, ceria, carbon, silica-alumina,silica nitride, and boron nitride. Furthermore, nanoporous supports suchas zeolites, carbon nanotubes, or carbon fullerene may be utilized. Fromamong these supports, silica is preferred.

[0112] The support may also be treated, as by surface-modification, toremove surface moieties such hydrogen and hydroxyl. Surface hydrogen andhydroxyl groups can cause local pH variations that adversely effectcatalytic efficiency. The support can be modified, for example, bytreating it with a modifier selected from the group consisting ofsilanes, alkali compounds, and alkali earth compounds. The preferredsupport is silica modified by treatment with trimethylethoxysilane.

[0113] Particularly useful catalyst systems for the practice of theinvention include, but are not limited to: ruthenium supported onsilica, palladium supported on silica, iridium supported on silica,platinum supported on silica, rhodium supported on silica, cobaltsupported on silica, nickel supported on silica, iron supported onsilica, nickel-palladium supported on silica, nickel-platinum supportedon silica, and ruthenium-palladium supported on silica. Preferably, thecatalyst system is platinum on silica or ruthenium on silica, witheither of these two metals being further alloyed or admixed with copper,zinc, and/or rhenium.

[0114] The catalyst system that is most useful in the reforming reactionof a specific oxygenated hydrocarbon compound may vary, and can bechosen based on factors such as overall yield of hydrogen, length ofactivity, and expense. For example, in testing performed with respect tothe vapor-phase reforming of ethanediol, the following results wereobtained. At 250° C., 1 atm., and an H₂O-to-carbon molar ratio of 15, inthe presence of various catalyst systems where the metal was supportedon silica, the following ranking of metals was obtained in terms ofinitial H₂ yield and stability:

Rh>Ni>Ru>Ir>>Co>>Fe

[0115] The catalyst systems of the present invention can be prepared byconventional methods known to those in the art. These methods includeevaporative impregnation techniques, incipient wetting techniques,chemical vapor deposition, magnetron sputtering techniques, and thelike. The method chosen to fabricate the catalyst is not particularlycritical to the function of the invention, with the proviso thatdifferent catalysts will yield different results, depending uponconsiderations such as overall surface area, porosity, etc.

[0116] The liquid phase reforming method of the present invention shouldgenerally be carried out at a temperature at which the thermodynamics ofthe proposed reaction are favorable. The pressure selected for thereactions varies with the temperature. For condensed phase liquidreactions, the pressure within the reactor must be sufficient tomaintain the reactants in the condensed liquid phase.

[0117] The vapor-phase reforming method of the present invention shouldbe carried out at a temperature where the vapor pressure of theoxygenated hydrocarbon compound is at least about 0.1 atm (andpreferably a good deal higher), and the thermodynamics of the reactionare favorable. This temperature will vary depending upon the specificoxygenated hydrocarbon compound used, but is generally in the range of100° C. to 450° C. for reactions taking place in the vapor phase, andmore preferably from 100° C. to 300° C. for vapor phase reactions. Forreactions taking place in the condensed liquid phase, the preferredreaction temperature should not exceed 400° C.

[0118] The condensed liquid phase method of the present invention mayalso optionally be performed using a salt modifier that increases theactivity and/or stability of the catalyst system. Preferably, themodifier is a water-soluble salt of an alkali or alkali earth metal. Themodified is added to the reactor along with the liquid reactants. It ispreferred that the water-soluble salt is selected from the groupconsisting of an alkali or an alkali earth metal hydroxide, carbonate,nitrate, or chloride salt. If an optional modifier is used, it should bepresent in an amount from about 0.5% to about 10% by weight as comparedto the total weight of the catalyst system used.

EXAMPLES

[0119] The following Examples are included solely to provide a morecomplete disclosure of the subject invention. Thus, the followingExamples serve to illuminate the nature of the invention, but do notlimit the scope of the invention disclosed and claimed herein in anyfashion.

[0120] In all of the Examples, off-gas streams were analyzed withseveral different gas chromatographs (GCs), including a Carle GC with a“Porapak Q”-brand column (Waters Corp., Milford, Mass.) to determinehydrogen concentrations, an HP 5890 GC with a thermal conductivitydetector and a “Porapak N”-brand column (Waters) to determine carbonmonoxide, carbon dioxide, methane, and ethane concentrations, and the HP5890 GC with a thermal conductivity detector and a “Hayesep D”-brandcolumn (Hayes Separation Inc., Bandera, Tex.) to determine methane,ethane, propane, butane, pentane, and hexane concentrations. Totalhydrocarbon and other volatile oxygenates were determined using an HP6890 GC with a flame ionization detector and an “Innowax”-brandcapillary column from Agilent Technologies, Palo Alto, Calif. (Note:Hewlett Packard's chromatography operations were spun off into AgilentTechnologies, a wholly independent business, in 1999.)

Example 1

[0121] Silica-supported metal catalyst systems were prepared using anevaporative impregnation technique according to the following procedure:(1) Cab-O-Sil EH-5 fumed silica (Cabot Corporation, Woburn, Mass.) wasdried for 24 hours at 393 K; (2) a solution containing the metalcatalyst was added to the silica; and (3) the resulting catalyst wasdried in air.

Example 2

[0122] A 4 wt % silica-supported ruthenium catalyst system (Ru/SiO₂) wasprepared according to the general method of Example 1. A ruthenium (III)nitrosyl nitrate solution (1.5 wt % ruthenium solution) was added to thedried silica to produce a 4 wt % Ru/SiO₂ catalyst system. The mixturewas stirred at room temperature for 30 minutes in an evaporation dishfollowed by heating to remove the excess liquid. The resulting catalystsystem was then dried at 393 K in air overnight, and was then storeduntil testing.

Example 3

[0123] A 4 wt % silica-supported palladium catalyst system (Pd/SiO₂) wasprepared according to the general method described in Example 1. A 10 wt% tetraamine palladium nitrate solution was diluted with water and thenadded to the dried silica to form a gel upon stirring. The gel was driedat room temperature for one day and further dried at 393 K overnight.The resulting Pd/SiO₂ catalyst system was then calcined in O₂ at 573 Kfor 3 hours.

Example 4

[0124] A 4 wt % silica-supported iridium catalyst system (Ir/SiO₂) wasprepared according to the general method of Example 1. A dihydrogenhexachloroiridate (IV) solution was added to the dried silica to producea 4 wt % Ir/SiO₂ catalyst system. The mixture was then stirred at roomtemperature for 30 minutes in an evaporation dish followed by heating toremove the excess liquid. The catalyst system was dried at 393 K in airovernight, and then stored until testing.

Example 5

[0125] A 5 wt % silica-supported platinum catalyst system (Pt/SiO₂) wasprepared through the exchange of Pt(NH₃)₄ ²⁺ with H⁺ on the silicasurface. The preparation procedure involved the following steps: (1)Cab-O-Sil EH-5 was exchanged with an aqueous Pt(NH₃)₄(NO₃)₂ solution(Aldrich Chemical, Milwaukee, Wis.) with the degree of exchangecontrolled by adjusting the pH of the silica slurry with an aqueous,basic solution of Pt(NH₃)₄(OH)₂; (2) the resulting material was filteredand washed with deionized water; and (3) and the filtered material wasdried overnight in air at 390 K.

Example 6

[0126] Catalyst systems produced using the methods of Examples 1 and 5were investigated for the vapor-phase reforming of an aqueous ethanediolsolution in the presence of water. In these investigations, 0.1 g of aspecific catalyst system was loaded into a glass reactor and reduced for8 hours at 450° C. in flowing hydrogen before being used. A 10 wt %ethanediol solution in water was introduced via a syringe pump at a rateof 0.2 cc/h to a heated line of flowing helium (100 sccm). The reactionmixture of ethanediol and water was passed through a preheat section tovaporize the aqueous ethanediol solution and then over the catalyst bedat temperatures between 275° C. and 300° C. The partial pressure ofethanediol was 0.001 atm and the water-to-carbon molar ratio was 15to 1.

[0127] The resulting gases were analyzed via an online GC equipped witha thermal conductivity detector. For these tests, the GC utilized ahelium carrier gas to maximize the detection of the carbon-containingproducts. In this mode, it was not possible to detect hydrogen directly,so the hydrogen production was determined indirectly from the amounts ofCO, CO₂, and CH₄ produced using the following equations:

1.5 moles of H₂ produced per mole of product CO

2.5 moles of H₂ produced per mole of product CO₂

2.0 moles of H₂ consumed per mole of product CH₄

[0128] Table 1 shows the effects of metal type on the conversion ofethanediol and product ratio of the carbon containing products. Thistable shows that at 275° C., the ruthenium catalyst system completelyconverted the ethanediol to CO₂, indicating that ruthenium not onlyeffectively cleaves the C—C bond of ethanediol, but also is an effectiveWGS reaction catalyst. Ethanediol was also completely converted overboth the platinum and palladium catalyst systems at 275° C., but thesemetals were not as effective for the WGS reaction. The iridium catalystsystem was not as effective for the complete conversion of ethanediol toH₂ at 275° C. However, elevating the temperature of theiridium-catalyzed reaction to 300° C. was sufficient to accomplishcomplete conversion. TABLE 1 Effect of Catalyst on Steam Reforming ofEthanediol. (Total pressure = 1 atm, ethanediol partial pressure = 0.001atm, water:carbon ratio = 15.5, GHSV = 72 std liter ethanediol feed perkg catalyst per h.) Carbon Containing Product Temperature ConversionRatio (%) Catalyst (° C.) (%) CO Methane CO₂ 4% Ru/SiO₂ 275 100 0 0 1004% Pt/SiO₂ 275 100 37.3 0 62.7 4% Pd/SiO₂ 275 100 100 0 0 4% Ir/SiO₂ 300100 22.2 0 77.8

Example 7

[0129] The 4 wt % Ru/SiO₂ catalyst system produced using the method ofExample 2 was investigated for the vapor-phase reactions of ethanediolin the presence of water with and without the addition of hydrogen gasin the feed. In the reactions of this Example, 0.5 g of the catalystsystem was loaded into a glass reactor and reduced for 8 hours at 450°C. in flowing hydrogen before being used. A solution of 10 wt %ethanediol in water was injected into a heated line and vaporized beforethe reactor via a HPLC pump at a rate of 3.6 cc/h. At this feed rate,the gas hourly space velocity (GHSV) was 260 std liter of ethanediol perkg catalyst per hour. The water-to-carbon molar ratio was 15:1. Thevaporized aqueous solution was then passed over the Ru/SiO₂ catalystsystem at a temperature of 300° C. at 1 atm. The liquid product wascondensed and the ethanediol concentration was analyzed via GC.

[0130] This same reaction was then repeated verbatim, with the soleexception that hydrogen was added to the feed at a rate of 3 moleshydrogen per 15 moles of H₂O per 1 mole of carbon (i.e., 3:15:1,H₂:H₂O:C).

[0131] The results are shown in FIG. 7, which shows the conversion ofethanediol as a function of time on stream. Table 2 shows the productratio of the carbon-containing products for this Example at 1 hour andat 117 hours. Table 2 shows that at 1 hour, the primary product was CO₂.After 117 hours of operation, the product ratio to CO₂ decreased with acorresponding increase of the product ratio for CO. FIG. 7 shows thatadding a hydrogen modifier to the reactor decreased the initial activityof the catalyst, but extended the useful operating life of the catalyst.FIG. 7 also shows that the conversion decreased from a high of 94% to74% over the course of 112 hours. Table 2 shows that at 1 hour, CO wasthe primary carbon-containing product and that the product ratio to COincreased as the catalyst deactivated. TABLE 2 Selectivity for the SteamReforming of Ethanediol over 4 wt % Ru/SiO₂ at 300° C., 1 atm, and GHSV= 260 std liter of ethanediol per kg catalyst per h. Time CarbonContaining Product Run On Conversion ORatio (%) Description Stream % COCO₂ CH₄ CH₃OH No H₂  1 h 98 1.3 96 2.7 0.04 No H₂ 117 h 44 45.1 54.8 0.20.00 H₂ in Feed  1 h 94 64.2 31.5 4.2 0.04 H₂ in Feed  66 h 80 88.5 11.00.5 0.00

Example 8

[0132] Silica-supported monometallic and bimetallic catalyst systemswere prepared by using the incipient wetting technique to add the givenmetal to the silica. The preparation procedure involved the followingsteps: (1) Cab-O-Sil EH-5 fumed silica was dried at 393 K; (2) the metalor metals were added to the silica by adding dropwise an aqueoussolution of the appropriate metal precursor (approximately 1.5 gram ofsolution per gram of catalyst); and (3) the impregnated catalyst wasdried at 393 K overnight. The catalyst systems were then stored in vialsuntil testing.

Example 9

[0133] Silica-supported monometallic and bimetallic catalyst systems,made via the procedure of Example 8, were tested for the vapor-phasereforming of ethanediol (i.e., ethylene glycol). Ten milligrams of agiven catalyst system was loaded into a glass reactor and reduced for 4hours at 450° C. in flowing hydrogen before use in the reaction. Anaqueous solution of 10-wt % ethanediol in water was introduced via asyringe pump at a rate of 0.2 cc/h to a heated line of flowing helium(50 sccm). The reaction mixture was passed through a preheat section tovaporize the aqueous ethanediol solution and then over the catalystsystem at a temperature of 250° C. The partial pressure of ethanediolwas 0.0023 atm and the water-to-carbon molar ratio was 15 to 1. Thegases were analyzed via an online GC equipped with a TCD detector. Atthe low conversions of these investigations, CO was the only productdetected. Accordingly, the production rate of CO was used tocharacterize both the activity and stability of the different metals.The results are shown in FIGS. 8, 9, 10, 11, and 12.

[0134]FIG. 8 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, at a molar water-to-carbon ratio of 15 over monometalliccatalyst systems containing Rh, Ni, Ru, Ir, Co, or Fe. This graph showsthat for monometallic catalysts systems, Rh displays the best activity,followed by, in order of decreasing activity, Ni, Ru, Ir, Co, and Fe. Ineach of the catalyst systems tested, the catalyst contained 1 wt % ofthe metal on a silica support.

[0135]FIG. 9 shows vapor-phase reforming of ethanediol at 250° C. and 1atm, and a water-to-carbon molar ratio of 15 over two different nickelcatalyst systems (1 wt % Ni/SiO₂ and 15 wt % Ni/MgO—Al₂O₃). These datashow that the metal loading and the support chosen can have significanteffects on catalytic activity. In FIG. 9, the closed circles representmolecules of CO per molecule of metal catalyst per minute for a 1 wt %Ni catalyst on a silica support. The open squares represent molecules ofCO per molecule of metal catalyst per minute for a 15 wt % Ni catalyston MgO—Al₂O₃. Quite clearly, this figure shows that the silica supportis much preferred over the MgO—Al₂O₃ support.

[0136]FIG. 10 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, at a water-to-carbon ratio of 15 over a bimetallic catalystsystem (Ni—Pd) as compared to monometallic Rh/SiO₂, Pd, and Ni catalystsystems. Here, four distinct catalyst systems were tested: 1.0 wt %Rh/SiO₂, 1Ni—2Pd (0.5 wt % Ni)/SiO₂, 4.0 wt % Pd/SiO₂, and 1.0 wt %Ni/SiO₂. As shown in FIG. 10, the Rh and Ni—Pd catalyst systems had verysimilar activities and stabilities over the course of 7 hours. The Pdcatalyst system had lower activity, but also exhibited a very constantactivity over the course of the study. The Ni catalyst system had verygood initial activity, but exhibited steadily declining activity overthe 7-hour course of the experiment.

[0137]FIG. 11 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, at a water-to-carbon ratio of 15 over various catalystsystems (Rh, Ni—Pt, Pt, and Ni). Here, four distinct catalyst systemswere tested: 1.0 wt % Rh/SiO₂, 1Ni—2Pt (0.5 wt % Ni)/SiO₂, 5.0 wt %Pt/SiO₂, and 1.0 wt % Ni/SiO₂. As shown in FIG. 11, the Ni catalystsystem again had good initial activity, but exhibited steadily decliningactivity over the course of the experiment. The rhodium catalyst systemexhibited high and steady activity over the course of the experiment,with the mixed Ni—Pt system exhibiting similar stability, but at a lowerlevel of activity. The Pt catalyst system exhibited still lower activityand also showed steadily decreasing activity over time.

[0138]FIG. 12 shows the vapor-phase reforming of ethanediol at 250° C.and 1 atm, at a water-to-carbon ratio of 15 over various catalystsystems (Rh, Ru—Pd, Pd, and Ru). Here, four distinct catalyst systemswere tested: 1.0 wt % Rh/SiO₂, 1Ru—2Pd (1.0 wt/o Ru)/SiO₂, 4.0 wt %Pd/SiO₂, and 1.5 wt % Ru/SiO₂. As in the earlier Examples, the Rucatalyst system again had good initial activity, but exhibited steadilydeclining activity over the course of the experiment. The Rh catalystsystem exhibited the best activity, followed by the mixed Ru—Pd catalystand the Pd catalyst. All three of these catalyst systems exhibitedconstant activity over the course of the experiment.

Example 10

[0139] The vapor-phase reforming of sorbitol with either a 1 wt %Rh/SiO₂ catalyst system or a 14 wt % Rh/SiO₂ catalyst system, preparedby the method of Example 1, was carried out at 425° C. and 1 atm, in thepresence hydrogen. For this investigation, a 5 wt % sorbitol solutionwas fed to the system at 7.2 cc/h. One (1) gram of Rh catalyst wasloaded into the reactor and pretreated with flowing hydrogen at 450° C.for 4 h. For this Example, a 5 wt % sorbitol solution was fed to thesystem at 7.2 cc/h and vaporized in either flowing helium or flowinghydrogen. Initially, the 1 wt % Rh/SiO₂ was utilized for the steamreforming of the 5 wt % sorbitol solution in the presence of helium suchthat the He:H₂O:C ratio was 3:32:1. Initially, the catalyst exhibitedcomplete conversion of sorbitol to CO₂ and H₂ over this catalyst. FIG.13 shows the conversion of sorbitol as determined by analyses of thereactor outlet gases. Conversion over 100% is attributed to experimentalerror in measuring flow rates of the partially condensable reactoroutlet gas stream. FIG. 13 shows that after the initially observedcomplete conversion of the sorbitol, the conversion decreased quicklywith time, indicating rapid deactivation of the catalyst.

[0140] It was then attempted to reform the 5 wt % sorbitol solution overa 14 wt % Rh/SiO₂ catalyst, with H₂ in the feed (H₂:H₂O:C=4/32/1). FIG.13 shows that this 14 wt % Rh/SiO₂ catalyst completely converted thesorbitol for over 80 h of time with no indication of deactivation. GCanalysis confirmed that the major products were carbon dioxide andhydrogen with trace amounts of methane and carbon monoxide.

[0141] The 14 wt % Rh/SiO₂ was catalyst was then treated in flowinghydrogen overnight at 450° C. and then used to reform a 10 wt % sorbitolsolution in the presence of helium (He:H₂O:C=3:16:1) at 450° C. FIG. 14shows that the 14 wt % Rh/SiO₂ completely converted the sorbitol forover 70 h. The helium sweep gas was removed after 70 h, and the catalystcontinued to convert the sorbitol essentially completely. In thisinvestigation, GC analyses showed only carbon dioxide was formed. Thecombined results shown in FIGS. 13 and 14 indicate that higher loadingsof metal enhance the lifetime of the catalyst. These two figures alsosuggest that the silica support may be involved in the deactivationmechanism.

Example 11

[0142] A 5 wt % silica-supported platinum catalyst system was madeaccording to the procedure described in Example 5. The catalyst was,however, modified by dehydroxylation and capping withtrimethylethoxysilane. The catalyst system was prepared as follows: (1)fumed silica (Cab-O-Sil, EH-5 grade) was dried at 600 K for 10 hoursunder flowing helium; (2) platinum was added to the support byvapor-phase deposition of Pt(II) acetylacetonate at 500 K; (3) theresulting Pt/SiO₂ catalyst system was calcined at 600 K in flowingoxygen; (4) the calcined catalyst system was reduced at 600 K withflowing hydrogen; (5) the resulting catalyst system was dehydroxylatedunder flowing helium at 1173 K; (6) the catalyst system was treated withCO at 300 K to prevent the platinum sites from reacting withtrimethylethoxysilane; (7) the resulting catalyst was dosed with 4.5mmol trimethylethoxysilane (Gelest, Inc., Tullytown, Pa.) at 300 K; (8)the catalyst was dosed with CO until the residual pressure was 10 torr;(9) trimethylethoxysilane was dosed onto the catalyst at 473 K; and (10)the resulting catalyst system was calcined with flowing oxygen at 373 K.The catalyst system contained 70 μmol/g of surface platinum asdetermined by dosing with carbon monoxide at 300 K.

Example 12

[0143] Liquid phase reforming of sorbitol was performed using themetallic catalyst systems described in Examples 5 and 11. The apparatusused for the reforming is the apparatus depicted schematically in FIG.5. The catalyst was loaded into a ¼ inch stainless steel reactor. Thecatalyst was reduced by flowing hydrogen across the catalyst at atemperature of 225° C. After reduction, the reactor was cooled. Thesystem was then purged with nitrogen, and a HPLC pump was used to fillthe reactor with a 10 wt % sorbitol aqueous solution. Once liquid wasobserved in the separator, the pressure of the system was increased to300 psig with nitrogen (the pressure is controlled by the backpressureregulator 26; see FIG. 5). While the liquid feed was pumped over thecatalyst bed, the furnace heated the bed to 225° C. The liquid exitedthe reactor and was cooled in a double-pipe water cooler (FIG. 5,reference number 22). The fluid from this cooler was combined with thenitrogen flow at the top of the cooler and the gas and liquid wereseparated in the separator 24.

[0144] The liquid was drained periodically for analysis, and the vaporstream passed through the back-pressure regulator 26. This off-gasstream was analyzed with several different GCs to determine the hydrogenconcentration, the carbon monoxide, carbon dioxide, methane, and ethaneconcentrations, and the methane, ethane, propane, butane, pentane, andhexane concentrations. Total hydrocarbon and other volatile oxygenateswere also determined by GC.

[0145]FIG. 15 shows the results for the liquid-phase conversion of a 10wt % sorbitol solution over the 5 wt % Pt/SiO₂ catalyst system ofExample 5 at 225° C. This figure shows the observed turnover frequencies(TOF, moles of product per mole of surface platinum per minute) for CO₂,H₂, and carbon found in paraffins. Additionally, FIG. 15 shows thehydrogen selectivity, which is defined as the observed hydrogenproduction divided by the hydrogen produced from the production of theobserved CO₂ (13/6 H₂ per CO₂ observed). FIG. 15 shows that 33% CO₂ wasobserved in the off-gas. After 22 hours (indicated by the vertical line10 in FIG. 15), the feed was switched to 10% glucose. FIG. 15 shows thatthe production of CO₂ increased without a significant change in the rateof hydrogen production. Accordingly, the H₂ selectivity decreased to 22%even after accounting for the lower theoretical yield of H₂ from glucose(13/6 H₂ per CO₂ observed).

[0146]FIG. 16 shows the result for the liquid-phase conversion of a 10wt % sorbitol solution at 225° C. over the 5 wt % Pt/SiO₂ catalyst thatwas defunctionalized by capping (see Example 11). This figure shows theobserved turnover frequencies (moles of product per mole of surfaceplatinum per minute) for CO₂, H₂, and carbon found in paraffins.Additionally, this figure shows the H₂ selectivity that again is definedas the observed hydrogen production divided by the hydrogen producedfrom the production of the observed CO₂. FIG. 16 shows that supportingplatinum on the modified silica enhanced both the rates of production ofCO₂ and H₂, as well as the H₂ selectivity. Importantly, this figure alsoshows that when KOH was added to the 10 wt % sorbitol solution, therates of H₂ production increased and the rate of paraffin productiondecreased. Additionally, the H₂ selectivity increased with the additionof KOH in the liquid feed. Importantly, as the KOH concentration isincreased from 0 M KOH to 0.006 M KOH, the H₂ selectivity increased from57% to 77%. In addition, the rate of H₂ production increased from 0.65min⁻¹ to 0.83 min⁻¹. This example clearly demonstrates that thecondensed liquid phase reforming of both glucose and sorbitol ispossible.

[0147] The significance of all of the Examples given above is that theydemonstrate that the vapor phase and condensed liquid phase reformationof oxygenated hydrocarbons to yield hydrogen is possible using a host ofdifferent types of Group VIII metal-containing catalysts.

What is claimed is:
 1. A method of producing hydrogen comprising:reacting water and a water-soluble oxygenated hydrocarbon having atleast two carbon atoms, in the presence of a metal-containing catalyst,wherein the catalyst comprises a metal selected from the groupconsisting of Group VIII transitional metals, alloys thereof, andmixtures thereof.
 2. The method of claim 1, wherein the water and theoxygenated hydrocarbon are reacted at a temperature of from about 100°C. to about 450° C., and at a pressure where the water and theoxygenated hydrocarbon are gaseous.
 3. The method of claim 1, whereinthe water and the oxygenated hydrocarbon are reacted at a temperature offrom about 100° C. to about 300° C., and at a pressure where the waterand the oxygenated hydrocarbon are gaseous.
 4. The method of claim 1,wherein the water and the oxygenated hydrocarbon are reacted at atemperature not greater than about 400° C., at a pressure where thewater and the oxygenated hydrocarbon remain condensed liquids.
 5. Themethod of claim 1, wherein the water and the oxygenated hydrocarbon arereacted at a pH of from about 4.0 to about 10.0.
 6. The method of claim1, wherein the catalyst comprises a metal selected from the groupconsisting of nickel, palladium, platinum, ruthenium, rhodium, iridium,alloys thereof, and mixtures thereof.
 7. The method of claim 1, whereinthe catalyst is further alloyed or mixed with a metal selected from thegroup consisting of Group IB metals, Group IIB metals, and Group VIIbmetals.
 8. The method of claim 1, wherein the catalyst is furtheralloyed or mixed with a metal selected from the group consisting ofcopper, zinc, and rhenium.
 9. The method of claim 1, wherein thecatalyst is adhered to a support.
 10. The method of claim 9, wherein thesupport is selected from the group consisting of silica, alumina,zirconia, titania, ceria, carbon, silica-alumina, silica nitride, andboron nitride.
 11. The method of claim 9, wherein the support issurface-modified to remove surface moieties selected from the groupconsisting of hydrogen and hydroxyl.
 12. The method of claim 9, whereinthe support is modified by treating it with a modifier selected from thegroup consisting of silanes, alkali compounds, and alkali earthcompounds.
 13. The method of claim 9, wherein the support is silicamodified with trimethylethoxysilane.
 14. The method of claim 9, whereinthe support is a zeolite.
 15. The method of claim 9, wherein the supportis a carbon nanotube or a carbon fullerene.
 16. The method of claim 9,wherein the support is a nanoporous support.
 17. The method of claim 1,wherein the water and the oxygenated hydrocarbon are reacted at atemperature not greater than about 400° C., at a pressure where thewater and the oxygenated hydrocarbon remain condensed liquids, andfurther comprising reacting the water and the water-soluble oxygenatedhydrocarbon in the presence of a water-soluble salt of an alkali oralkali earth metal.
 18. The method of claim 17, wherein thewater-soluble salt is selected from the group consisting of an alkali oran alkali earth metal hydroxide, carbonate, nitrate, or chloride salt.19. The method of claim 1, wherein the water-soluble oxygenatedhydrocarbon has a carbon-to-oxygen ratio of 1:1.
 20. The method of claim1, wherein the water-soluble oxygenated hydrocarbon has from 2 to 12carbon atoms.
 21. The method of claim 1, wherein the water-solubleoxygenated hydrocarbon is selected from the group consisting ofethanediol, ethanedione, glycerol, glyceraldehyde, aldotetroses,aldopentoses, aldohexoses, ketotetroses, ketopentoses, ketohexoses, andalditols.
 22. The method of claim 1, wherein the water-solubleoxygenated hydrocarbon is selected from the group consisting ofaldohexoses and corresponding alditols.
 23. The method of claim 1,wherein the water-soluble oxygenated hydrocarbon is selected from thegroup consisting of glucose and sorbitol.
 24. The method of claim 1,wherein the water-soluble oxygenated hydrocarbon is sucrose.
 25. Amethod of producing hydrogen comprising: reacting water and awater-soluble oxygenated hydrocarbon having at least two carbon atoms,at a temperature not greater than about 400° C., at a pressure where thewater and the oxygenated hydrocarbon remain condensed liquids, and inthe presence of a metal-containing catalyst, wherein the catalystcomprises a metal selected from the group consisting of Group VIIItransitional metals, alloys thereof, and mixtures thereof.
 26. Themethod of claim 25, wherein the catalyst comprises a metal selected fromthe group consisting of nickel, palladium, platinum, ruthenium, rhodium,iridium, alloys thereof, and mixtures thereof.
 27. The method of claim25, wherein the catalyst is further alloyed or mixed with a metalselected from the group consisting of Group IB metals, Group IIB metals,and Group VIIb metals.
 28. The method of claim 25, wherein the catalystis further alloyed or mixed with a metal selected from the groupconsisting of copper, zinc, and rhenium.
 29. The method of claim 25,wherein the catalyst is adhered to a support.
 30. The method of claim29, wherein the support is selected from the group consisting of silica,alumina, zirconia, titania, ceria, carbon, silica-alumina, silicanitride, and boron nitride.
 31. The method of claim 29, wherein thesupport is surface-modified to remove surface moieties selected from thegroup consisting of hydrogen and hydroxyl.
 32. The method of claim 31,wherein the support is modified by treating it with a modifier selectedfrom the group consisting of silanes, alkali compounds, and alkali earthcompounds.
 33. The method of claim 29, wherein the support is silicamodified with trimethylethoxysilane.
 34. The method of claim 29, whereinthe support is a zeolite.
 35. The method of claim 29, wherein thesupport is a carbon nanotube or a carbon fullerene.
 36. The method ofclaim 29, wherein the support is a nanoporous support.
 37. The method ofclaim 25, further comprising reacting the water and the water-solubleoxygenated hydrocarbon in the presence of a water-soluble salt of analkali or alkali earth metal.
 38. The method of claim 37, wherein thewater-soluble salt is selected from the group consisting of an alkali oran alkali earth metal hydroxide, carbonate, nitrate, or chloride salt.39. The method of claim 25, wherein the water-soluble oxygenatedhydrocarbon has a carbon-to-oxygen ratio of 1:1.
 40. The method of claim25, wherein the water-soluble oxygenated hydrocarbon has from 2 to 12carbon atoms.
 41. The method of claim 25, wherein the water-solubleoxygenated hydrocarbon is selected from the group consisting ofethanediol, ethanedione, glycerol, glyceraldehyde, aldotetroses,aldopentoses, aldohexoses, ketotetroses, ketopentoses, ketohexoses, andalditols.
 42. The method of claim 25, wherein the water-solubleoxygenated hydrocarbon is selected from the group consisting ofaldohexoses and corresponding alditols.
 43. The method of claim 25,wherein the water-soluble oxygenated hydrocarbon is selected from thegroup consisting of glucose and sorbitol.
 44. The method of claim 25,wherein the water-soluble oxygenated hydrocarbon is sucrose.
 45. Amethod of producing hydrogen comprising: reacting water and awater-soluble oxygenated hydrocarbon having at least two carbon atoms,at a temperature of from about 100° C. to about 450° C., and at apressure where the water and the oxygenated hydrocarbon are gaseous, inthe presence of a metal-containing catalyst, wherein the catalystcomprises a metal selected from the group consisting of Group VIIItransitional metals, alloys thereof, and mixtures thereof, the catalystbeing adhered to a support.
 46. The method of claim 45, wherein thesupport is selected from the group consisting of silica, alumina,zirconia, titania, ceria, carbon, silica-alumina, silica nitride, andboron nitride, modified to remove surface moieties selected from thegroup consisting of hydrogen and hydroxyl.
 47. The method of claim 46,wherein the support is modified by treating it with a modifier selectedfrom the group consisting of silanes, alkali compounds, and alkali earthcompounds.
 48. The method of claim 45, wherein the support is silicamodified with trimethylethoxysilane.
 49. The method of claim 45, whereinthe water-soluble oxygenated hydrocarbon has a carbon-to-oxygen ratio of1:1.
 50. The method of claim 45, wherein the water-soluble oxygenatedhydrocarbon is selected from the group consisting of ethanediol,ethanedione, glycerol, glyceraldehyde, aldotetroses, aldopentoses,aldohexoses, ketotetroses, ketopentoses, ketohexoses, and alditols. 51.A method of producing hydrogen comprising: reacting water and awater-soluble oxygenated hydrocarbon having at least two carbon atoms,at a temperature of not greater than about 400° C., and at a pressurewhere the water and the oxygenated hydrocarbon remain condensed liquids,in the presence of a metal-containing catalyst, wherein the catalystcomprises a metal selected from the group consisting of Group VIIItransitional metals, alloys thereof, and mixtures thereof, the catalystbeing adhered to a support.
 52. The method of claim 51, wherein thesupport is selected from the group consisting of silica, alumina,zirconia, titania, ceria, carbon, silica-alumina, silica nitride, andboron nitride, modified to render to remove surface moieties selectedfrom the group consisting of hydrogen and hydroxyl.
 53. The method ofclaim 52, wherein the support is modified by treating it with a modifierselected from the group consisting of silanes, alkali compounds, andalkali earth compounds.
 54. The method of claim 51, wherein the supportis silica modified with trimethylethoxysilane.
 55. The method of claim51, wherein the water-soluble oxygenated hydrocarbon has acarbon-to-oxygen ratio of 1:1.
 56. The method of claim 51, wherein thewater-soluble oxygenated hydrocarbon is selected from the groupconsisting of ethanediol, ethanedione, glycerol, glyceraldehyde,aldotetroses, aldopentoses, aldohexoses, ketotetroses, ketopentoses,ketohexoses, and alditols.